Packaging method and machine



May 4, 1965 K. G. CLARK ETAL PACKAGING METHOD AND MACHINE 'rSmeets-sheet 1 Filed June 13, 1962 May 4, 1965 K. G. CLARK ETALPACKAGING METHOD AND MACHINE 7 Sheets-Sheet 2 Filed June l5. 1962 May 4,1965 K. G. CLARK E'rAL 3,181,956

PACKAGING METHOD AND MACHINE Filed June 15, 1962 'T Sheets-Sheet 3 May4, 1965 K. G. CLARK ETAL PACKAGING METHOD AND MACHINE '7 Sheets-Shed?I 4Filed June 13, 1962 May 4, 1965 K. G. CLARK ETAL PACKAGING METHOD ANDMACHINE 7 Sheets-Sheet 5 Filed June 13, 1962 May 4, 1965 K. G. CLARKETAL PACKAGING METHOD AND MACHINE 7 Sheets-Sheet 6 Filed June 13, 1962 XZOTFO m N 20:02 nl lli. \\\`& N s -lllw i- LL/ r May 4, 1965 K. G. CLARKETAL 3,181,956

' PACKAGING METHOD AND MACHINE Filed June 13, 1962 7 Sheets-Sheet '7United States Patent O 3,181,956 PACKAGING METHOD AND MACHINE Kenneth G.Clark, Homewood, Michael J. Myles,

Downers Grove, and Harry P. Eichin, Western Springs,

Ill., assignors to Union Carbide Corporation, a corporation of New YorkFiled June 13, 1962, Ser. No. 202,106 9 Claims. (Cl. 99-174) Thisinvention relates to the art of packaging a group of assembled items inan envelope of ilexible film. More particularly, the invention isconcerned with improvements in packaging whereby a preselected group ofitems, such as frankfurters, is encased Within an envelope comprising atubular wall of elastic film that is tensioned about the encased itemsto form a tightly adhering shapecontorming wrap.

The invention provides a novel method of and means ttor substantiallyincreasing the rate of lling elastic plastic bags yfor example, withpreselected contents, the perimeter of which is greater than that of thebag to be iilled, while decreasing Waste due to 'bag breakage, Whichcomprises rst stretching the bag about %-20% more tha its original size,then heating and relaxing such bag, *further stretching the bag anadditional amount about equal to such -iirst stretching, and iinal-lyfilling the sofinally-stretched bag with such contents While releasingthe bag into tensioned engagement therewith.

The invention further provides novel apparatus having lautomaticallycontrolled means tor simultaneously cir- 'cumferentially part-lyexpanding substantially the entire length of an elastic iilm bag, thenheating and relaxing the bag .in a first step; lthen fully expanding andmaintaining the bag in such expanded 'condition to a predeterminedlarger perimeter in a second step; means coordinated with said expandingmeans to convey the assembly of items to the mouth of the expanded bag,and insert the assembly of items into s-aid bag subsequent to its havingbeen fully expanded, in a third step.

The invention also provides a novel method of packaging a plurality ofgenerally similar elongated items arranged in side-by-side relation,which comprises holding such items in an open end support, applying on astretcher an envelope comprising a tubular Wall of elastic plastichaving a mouth which is smaller than the transverse dimension-s ot saidmembers, stretching such tubular Wall, heating and relaxing theso-stre'tched Wall on said stretcher, again stretching the Wall tofurther enlarge such mouth, aligning such enlarged mouth with the itemsin such support, and pushing all of such items through the support andinto the envelope through such enlarged mouth Vwhile simultaneouslyslipping the tubular wall `from p such stretcher, progressivelyshrinking the iilm about the sci-inserted items.

The main object of the invention is greatly to increase the productionrate of packaging, while reducing substantially the volume of Waste dueto breakage.

Another object is to provide for increasing the eiliciency andeffectiveness of packaging of the kind herein involved.

Other objects will appear from the present disclosure.

A prior method of packaging is disclosed in U.S. Patent 2,884,328, E. O.Johnson. A packaging rate of only about 12 twodpound frankurter packagesper minute, could be attained thereby. At such rate, the elastic bag had.to be fully expanded in a time interval of less than about 0,75 second.

Such frankfurter packaging opera-tions were normally carried on within aproduct ,cooler room maintained rat about 40 F. The cold environment orapparatus and product and the rapid stretching of the thin Walls andbottom closure of the elastic bags used in the operation,

adversely affected the utility of the bag, resulting in undesirablefrequency ot" bag breakage.

According to the present invention, which is particularly adapted to thepackaging of a rectangular -assembly of unit items as for example, twopounds ot `frankfurter Iproduct in a bag of elastic iilm to yield apackage item wherein the frankfurters are tightly wrapped and snuglyconformed Within .the Ibag Walls comprising the elastically stretchedlm, the bag, Whose normal stretched perimeter is smaller than themaximum perimeter of the frankfurter items transverse to theirlongitudinal axes, is simultaneously elas-tically stretchedcircumferentially along substantially its entire length to ya largerperimeter than the assembled frankfurter items. The method of thepresent invention may be practiced at a packaging rate of about 25two-pound frankfurter packages per minute. Such rap-id rate i-s attainedby this invention Without adversely affecting bag breakage, bymultistage expanding and relaxing of the bag walls, at a controlledrate, and by hearting the bag and the stretching linger-s, and byexpanding the bag simultaneously circumlerentially along its entirelength to a larger perimeter than the predetermined perimeter of theassembled frankfurters, and by advancing the product to the bag bottomto strip the bag from the expand-ed ngers at a controlled rate.

The novel method and apparatus of this invention packages irankfurtersat twice the rate off 'the former method. `By controlled heating ot thebag and expanding lingers, by expanding-relaxing-expanding the bag in amultistage operation in a time interval three times longer, and bycontrolling the impact of product on the bag bottom closure and Walls asthe bag is stripped from the lingers, the utility of the elastic bagsused inthe operation is substantially improved.

`In the `accompanying drawings, likeV reference characters designate thesame or similar parts in the various views, said drawings showingconstruction details and mode of operation of a typical apparatusembodying this invention and fw-herein:

FIGURE l is a front perspective View of Ian apparatus embodying theinvention and generally showing assembled groups of ifranlcfurterproduct being conveyed to an elastic iilm bag stretched throughout itslengths by a set o'f parallel movably mounted stretching lingers.

`FIGURE 2 is a rear perspective view of the apparatus driving mechanism@coordinated tor conveying assembled groups or product to lan insertingstation, for expanding and contracting tour sets of bag stretchinglingers in parallel movement to each other, and rfor removing a lled bagtrom a set of expanded `lingers While concurrently longitudinallyelastcally stretching the bag over the product.

IFIGURE 3 is a rear elevation of the apparatus turret head with foursets ot parallel stretching lingers and internal cam mechanismcoordinated for expanding and contracting four linger-formed passages.

FIGURE 4 is a fragmentary front elevation of the apparatus turret headwith one set of parallel stretching fingers and associated operatingmeans, in expanded position as indexed at a product loading station.

FIGURE 5 is a fragmentary front perspective of the apparatus at theproduct loading station with bag removed from the stretching lingers toshow the product pusher plunger in retracted position.

FIGURE 6 is a front perspective of the internal cam in an alternateembodiment of the apparatus that cooperates with mechanism forsuccessively partly-expanding then contracting, and then furtherexpanding four lingerformed passages.

FIGURE 7 is a section along/the line 6--6 of FIG- URE 4.

FIGURE 8 is a fragmentary rear perspective of the apparatus at theproduct loading station with the product pusher plunger and associatedoperating means in retracted position, and indexed therewith a loadedproduct trough and bag stretched over an expanded finger-formed passage.

FIGURE 9 is a fragmentary front perspective of the apparatus at anintermediate station, With a partly expanded finger-formed passageindexed between a tandem heater unit.

FIGURE 10 is a fragmentary side elevati-on of the pusher plungeroperating means.

FIGURE 11 is a front elevation of the pusher plunger.

FIGURE l2 is a diagram of the acceleration curve of the pusher plungeradvance and retract motion.

FIGURE 13 is a schematic perspective of the apparatus drive and controlmeans.

FIGURE 14 is an electrical wiring diagram of the apparatus.

The preferred embodiment of the improved packaging apparatus of thisinvention, as shown in FIGURES 1 and 2, comprises a rigid main frame 10,supported by attached legs 12; and a conveyor drive arrangement 14, fortransporting assembled product items to a product loading station 6. Asquare turret head 16 is rotatably mounted on an intermittently operatedhorizontal driving shaft 18. Four sets of bag-stretching linger units A,B, C, D, are operably mounted at the extremities of the turret headdiagonals. Each linger unit has an adjustably stationary linger mountingblock 20, and a movable linger mounting block 22.

Finger unit A is successively intermittently rotatably indexed clockwise90 at each packaging cycle from bag loading station 2 at three oclockposition, whereat the lingers are retracted and an elastic film bag 24is manually sheathed thereon, to intermediate station 4 at six oclockposition. The movable linger 22 of unit A is slidably moved parallelinwardly from the stationary finger 20 along the turret head 16 diagonal(by means later described), as it is indexed from station 2 to station 4(adjacent station 4, linger 22 is moved slightly outwardly), therebypartly expanding the bag 24 sheathed on the lingers 20, 22. At station4, finger unit A has expanded the bag 24 to approximately 50% of thedesired finished package perimeter.

At the next packaging cycle, linger unit A is rotatably indexed 90 fromstation 4, to product loading station 6 at nine oclock position, whereatlingers 20, 22 and the bag 24 sheathed thereon, are fully parallelexpanded to a perimeter greater than that of the desired linishedpackage. Refer additionally to FIGURES and 7. The product items 34 arepreviously assembled in a plurality of pr-oduct trough units 32, eachfastened to roller chain conveyer 30. The product trough units 32 aresuccessively indexed to station 6 where the product items are removedtherefrom by a controlled acceleration pushing motion of plunger surface40 transverse to conveyer 30, through the passage 28 formed by theexpanded lingers 20, 22 to engage the stretched bag bottom. Bycontinuation of the controlled motion of the plunger, the product stripsthe stretched bag from the linger-formed passage. At the next succeedingpackaging cycle linger unit A is rotatably indexed 90 from station 6, toidle station 8 at twelve oclock position. At the succeeding packagingcycle, linger unit A is rotatably indexed from station 8 to return tostation 2 at the three oclock position. As linger unit A is indexedsuccessively through two package cycles to rotate from station 6 tostation 2, movable linger block 22 is moved outwardly toward thestationary linger 20 along the turret head 16 diagonal to a contractedpositi-on permitting the sheathing thereon of another elastic bag 24.

Finger stretcher units B, C, D, are similar to unit A and arerespectively mounted and operated on turret head 16 in a like manner bylike means. Conveyer drive arrangement 14 comprises a continuoushorizontal chain conveyer 30 mounting a plurality of product troughs 32.Each product trough 32, preferably made of polished metal, is of apredetermined Width and height to cradle the desired number offrankfurters 34 to the perimeter of the desired finished package. Theproduct troughs 32 are loaded with the desired number and/or weight offrankfurters, by several operators stationed along the conveyer remotefrom product loading station 6.

At each successive package cycle, a unit trough 32 loaded with product34 is intermittently advanced and indexed central and opposite to theproduct loading station 6. A rectangular pusher plunger unit 38 with aperforate surface 40 of a perimeter less than the product trough 32 isslidable mounted central and opposite to loading station 6. When alinger unit such as A, and a product trough 32 are appropriatelysimultaneously indexed at station 6, the pusher plunger surface 40 is.advanced (as later described) to engage the product items assembledtherein and slide them from the trough 32 through the expandedlinger-formed passage 28 to engage the stretched bag 24 bottom, andcontinuing the advance, cause the encased product to strip the stretchedbag completely from the -outside surfaces of expanded passage 28.

An electric motor 42, FIGURES 2 and 13, drives a V-belt drive 44connected to a shaft-mounted speed reducer 46. The speed reducer 46 ismounted on main drive shaft 48 and braced to frame 10 by strut 50. Onmain drive shaft 48 is mounted a cam 52 for actuating an electricalswitch 54 controlling an indexing interlock with the drive motor 42(later described), a spur gear 56 mating with spur gear 58 for drivingintermittently indexing drive unit 60, and bevel gear 62 mating withbevel gear 64 fastened to shaft 65, driving product pusher face cam 66.

The intermittent rotation of the output of indexing drive 60 is directlyconnected by coupling 61 to turret head drive shaft 18, on the outboardend of which is affixed the turret head 16. Refer additionally to FIGURE8. Intermediate the turret head 16 and drive unit 60 on shaft 18, ismounted sprocket 68, that drives continuous roller chain 70 mating withsprocket 72 that is mounted on conveyer shaft 74. Two spaced sprockets76, 76', also mounted on shaft 74, drive parallel spaced continuousroller chains 78 to which are outwardly aliixed a plurality of producttroughs 32.

Referring now to FIGURES 2, 3, 4, internal surface cam 80 is aixed tobracket 82 and thereby to frame 10. Internal surface 86 of cam 80 is ofa generally ovate contour shaped to rapidly expand the bag 24 looselysheathed on the linger unit at station 2 at the beginning of a`packaging cycle, as one of the four bag stretching units such as A, isrotated from station 2 to station 4. Cam 80 is fixedly mounted to frame10 with its major axis horizontal and eccentric to the centerline ofshaft 18. Cam followers 84 are slidably mounted on turret head 16 tooperate radially to the axis 18 and parallel to the diagonals of head16, and are resiliently urged against the contoured inner surface 86 ofcam 80. As the turret head 16 is intermittently rotatably indexed, camfollowers 84 linked to respective movable linger blocks 22, govern therelative displacement of movable linger blocks 22 coordinated to expandand contract the four linger-formed passages. When the turret head 16moves from station 2 to station 4, cam follower 84 follows the camcontour 86, and linkage connecting the movable linger thereto partlyexpands the bag sheathed on the lingers.

In an alternate embodiment, the machine is provided with thelinger-expanding internal cam 81 shown in FIG- URE 6. Internal surface86 of cam 81 is of a generally about the finger-formed passage.Immediately prior to termination of the cycle, cam follower 84 is urgedinto depression 87 thereby slightly contracting the finger-formedpassage and permitting the walls of the partly-stretched bag to relaxabout the surfaces of the stretching fingers thereby equilibrating thestresses in the partly stretched bag walls prior to the heating thereof.

Each cam follower 84, FIGURES 3 to 7, is affixed to a grooved slideblock 88, slidably mounted in parallel guide ways 90 affixed to turrethead 16, and operating in slot 91 cut through the turret head. The camfollower 84 operates adjacent the back surface of turret head 16,coordinating the motion of slide block 88, slidably mounted on the frontsurface of the turret head 16. Connecting rod 92 rigidly fastens slideblock 88 to movable finger block 22 spaced outwardly therefrom. Each ofthe finger blocks 22, is slidably mounted on parallel slide rods 94equally spaced about the centerline of the diagonals of turret head 16.The inboard end of rods 94 are rigidly fastened into L-shaped brackets96, that are aiiixed to the front surface of turret head 16. Anintermediate portion of rods 94 is supported by adjustable stop brackets96, that are adjustably, slidably fastened to the front surface ofturret head 16 by suitable fastening means engaging slots 100.

The outboard end of rods 94 adjustably, slidably support the extremitiesof stationary finger block 20. Cornpression springs 102 slidablysupported on rods 94 intermediate the surfaces of brackets 96 and block22, resiliently urge the movable finger block 22 outwardly, limiting itsoutward movement -by contact with stop brackets 96. Operation of camfollower 34 on contoured surface S6 by means of the connecting linkagedescribed, urges the movable finger block 22 inwardly therebycompressing springs 102 and expanding the elastic bag sheathed on thefingers. The fingers are closed to contracted position by resilientpressure of springs 102, thus insuring a safe manual operation insheathing the bag on the fingers.

The finger blocks 20, 22, FIGURES 4, 5, 7, are provided with slide ways106 machined to mate with grooves provided in finger brackets 104, Sthat are respectively adjustably fastened thereto. Thus, the position ofthe lingers may be adjusted radially and centrally with respect to theturret axis 1S and thereby provide means to align the axis of theexpanded finger-formed passage 28 with the axis of the pusher unit 38 atproduct loading station 6.

Finger brackets 104, 105 are similarly machined with a groove that mateswith the tongue 108, of finger blades 112, 114. Finger blades 112, 114are fastened to brackets 104i, 105 by a ball detent holding pin 110.This arrangement permits a ready and quick interchange of finger bladesof different shapes contoured to different product assembly shapes ontomating finger blocks. The stationary finger comprises an arcuate shaped,extended metal finger blade 112 preferably having smooth polishedsurfaces to avoid abrasion and/or tearing of the bag film and productitems, and having sanitary surfaces as for example stainless steel orchromium plated surfaces. The movable nger blade 114 similar in shapeand length to stationary finger blade 112, is provided with a t'op andbottom skirt 116 that is an extension of the arcuate upper and lowerfinger blade edges having a length approximately 1/3 the blade lengthand width suiiicient to bridge the passage 2t? formed by the blades 112,114 in expanded position.

Skirt 116 bridges or spans that portion of the passage intermediateproduct trough 32 and the mouth of expanded bag 24 to prevent theproduct items from being dropped through the open fingers or from beingsnagged or caught by the bags expanded mouth.

Pusher unit shown generally as 33, FIGURES 8, l0, is intermittently,reciprocally operated at controlled acceleration and deceleration ratesto contact and advance a plurality of fragile nested resilient foodproduct items 341 from product trough 32, centrally to and throughexpanded finger-formed passage 23 to conform snugly to f5 the bag 24bottom, without damage, and to encase the product in the stretched bagconcurrently as the encased product is stripped completely from theexpanded fingers.

The pusher unit 3E intermittently advances and retracts during the dwellportion of the cycle of indexing drive 60. The necessary speed ofoperation, cushioning action for the product and complete removal of thefilled bag by the pusher plunger, is obtained by constant rotation offace cam 66. Refer now to FIGURE 12, representing a graph of the facecam 66 angular displacement, plotted against displacement of the pusher38 plunger through linkage shown on FIGURE l0 (later described).

The cam contour groove 119 and associated linkage provi-des a 120 dwellwith the pusher plunger in retracted position. As the face cam rotatesthe next 'the cam groove 119 advances the pusher by cycloidalaccelerated motion X, and in the next 40, advances the pusher byharmonic decelerated motion Y. As the cam rotates the next the camgroove 119 retracts the pusher by harmonic accelerated and deceleratedmotion Z."

Pusher unit 38 has a skirt 118 ciroumscribing the perimeter of surface40. Skirt 118 is of a length greater than the space intermediate thepusher surface 40 in its furthest advanced position and the outboardextremities of the expanded finger blades 112, 114, and serves to guidethe bag-encased product from the fingers and preveut collapse of the bagwalls trailing the encased product. The pusher plunger front surface 40is perforated with a plurality of holes 41 to relieve air pressure inthe bag caused by the product advance therein and by the vacuumotherwise created by the plunger return stroke. Vacuum caused by areturn stroke can `dislodge a product unit item from snug contact withthe bag bottom and extract it from the package.

The cam groove 119 mates with cam follower 120 that is afiixed toconnecting rod 122 intermediate its fulcrum bearing 12d rotatablyfastened to frame 10, and clevis crosshead 12d. Clevis crosshead 12.6 isfixedly fastened to pusher drive rod 123 that fixedly mounts pusherplunger 35 at one extremity and slide block 130 at the other extremityof drive rod 12S. Parallel guide rods 132, 132 are equally spaced aboutthe centerline of rod 128 that determines the axis of product loadingstation 6, and are afiixed in guide rod blocks 134, 13rd fastened toframe 1u.

As shaft e5 rotates continuously, the cam groove contour advances andretracts pusher drive rod 128 through forward bearing 137 in block 136,the other end of drive rod 123 being guided by block 130 sliding on rods132, 132. Pusher plunger 38 thereby cooperates with the product inpreviously indexed product trough 32, and the finger-formed passage ofan expanded finger unit such as A, aligned with the pusher plungerlongitudinal axis.

Another important feature of the apparatus, FIGURES 3, 9, provides forthe heating of finger blades 112, 114 and the partly expanded elasticbag 24 at stations 8 and d. Tandern curvilinear electrical resistanceheater units are positioned central of stations 4 and 8, and arecomprised of two 200 watt curved heater elements. An upper heaterelement 13S and lower heater element 140 are fastened onto electricalconnecting boxes 139, 139 in turn affixed to bracket 142 mounted onframe 10. Heaters 138, 1410 at stations 4 and are spaced apartrespectively, a distance approximately 1/2 greater than the span of thepartly expanded finger blades at each of said stations. Electricalcurrent for the heat elements 13%, 1li-0 is provided by wires 14d, 144.

The electrical control system for the apparatus drive is shown inFIGURES 13 and 14. At routine starting and stopping of the apparatus, itis desirable that the turret head 16 be indexed to the dwell portion ofa cycle that the pusher plunger is in retracted position. Closing theLstart button of push button station 146 closes control relay 148 thatin turn closes contactor motor starter `generally shown as 150,energizing motor 42 with line voltage L1L2L3. The magnetic hold-in 152of the starter 150 is in series with cam limit switch 54 and controlrelay 148. Cam switch 54 is opened by the depression in cam 52 whenturret head 16 is indexed to dwell position. When the stop button ofpush button station 146 is opened, relay 14S opens, but starter hold-in152 keeps the starter 15) contacts closed, until cam switch S4 opens,thereby opening the hold-in circuit 152, and the starter 150 contactsopen and motor 42 stops.

For operator safety, a normally open foot pedal switch 154 is providedthat is a master control on the lun circuit and must be depressed at alltimes to maintain operation. Foot pedal switch 154 is in series with L1and the stop side of push button station 146, and when switch 154 isreleased to open, the hold-in circuit of starter is immediately brokenand the starter 15) contacts open and motor 42 stops.

Another embodiment of the apparatus is particularly adapted to thepackaging in flexible film bags, of long length product items such asfoot-long frankfurters, meat loaves, and the like. This embodiment isprovided with two independently operated pusher plunger units; a primarypusher positioned central to station 6 and a secondary pusher positionedcentral to station 8. Machine components of this embodiment are similarto those shown in FIGURES l and 2 of the preferred embodiment andoperate in a like manner. A square turret head 16 mounts four sets ofelongated bag-stretching finger units A, B, C, D, intermittently indexedto four stations 2, 4, 6, S, as described supra. The finger-formedpassages are successively indexed to the bag loading station 2(retracted passage) at the three oclock position, and thence tointermediate station 4 (partly-expanded passage at the six oclockposition by means disclosed in the appzrratus of the preferredembodiment. However, at product loading station 6 (fully-expandedpassage), nine oclock position, the primary pusher assembly is arrangedto advance the product items from trough units 32 fully into theexpanded finger-formed passage, but not to strip the bag therefrom. Theproduct items thus are held within the expanded bag-encasedfinger-formed passage at station 6 and advanced therein to station 8. Asecondary pusher unit is aligned with station 8. The secondary pusherunit is coordinated to advance the product items through the passage tothe bag bottom and strip the bag from the expanded finger-formedpassage. The next cycle, advances the finger-formed passage to station2, where the fingers are retracted to receive another bag. This mode ofoperation permits advancing the primary pusher unit only the length ofthe product at station 6, thereby deferring for the next cycle ofoperation the time required to strip the bag from the fingers, by thesecondary pusher unit positioned at station 3. Thus, dwell time of themachine is not adversely affected by bag packaging of elongated productitems, since a two-step dofiing action is provided for loading theproduct into the expanded finger-formed passage in a first step atstation 6, and stuffing the product in a second step at station 8.

The following is an illustrative example of the operation of thepreferred embodiment of the apparatus. Eighteen franks Weighing 11/2pounds are nested in generally parallel relationship as a substantiallyrectangular prism in product troughs 32 with the machine set to operateat cycles per minute. A 51/2 fiat width (11" circumference) Visten pouchbag (of seamless plasticized polyvinyl chloride film) is sheathed on thefinger-formed passage retracted to 9" perimeter at station 2. During thefirst cycle, the bag is partly stretched to 13 perimeter, at station 4during the turret head 16 dwell period. While at station d, the bag isheated by the tandem electrical heaters 133, 14@ to about 45 F. over theambient temperature. This elevated tempera- 8 ture improves the stretchcharacteristics of the film and promotes removal of the bag-encasedproduct from the stretching fingers. During the next cycle, the bag isfully stretched to a 15" perimeter at station 6.

It will be understood that the stroke of the pusher is of such extentand is so correlated with the operation of the machine that the entirecontents of the trough is pushed into the bag until such contentsreaches the bottom of such bag, and thereby pushes and strips thesofilled bag progressively from the fingers holding the bag in fullystretched condition, and such pusher is thereupon fully retracted fromthe so-filled bag and into position for another stroke.

As will be understood from the foregoing disclosure, an importantfeature of the present invention is what may be termed equilibration orequilibrating of cold film on the stretcher between the start and finishof the overall stretching operation. This is accomplished in one or moreof the steps comprising: the pause or delay in the overall stretching ofthe film; heating of the film and stretcher-fingers to conditionfavorably the film for further stretching after it has first been atleast partially stretched; and relaxing the film by slightly contractingthe stretching fingers, thereby permitting it to rearrange itself on thefingers of the stretcher during such pause or delay in the overallstretching process.

As used herein, the term film is not necessarily limited to butincludes: plasticized polyvinyl chloride films; synthetic rubber films;cellulosic films; polyolefin films such as polyethylene andpolypropylene, and the like.

What is claimed is:

l. Method of packaging a plurality of elongated items arranged inside-by-side relation, which comprises holding such items in an open endsupport, applying on a stretcher an envelope comprising a tubular wallof elastic film having a mouth which is smaller than the transversedimensions of said members, stretching such tubular wall, heating saidfilm and relaxing the wall by slightly retracting said stretcher, againstretching the wall to further enlarge such mouth, aligning suchenlarged mouth with the items in such support, and pushing all of suchitems through the support and into the envelope through such enlargedmouth while simultaneously slipping the tubular wall from suchstretcher, whereby said film progressively shrinks about the so-inserteditems.

2. Method of filling elastic film bags with contents the perimeter ofwhich is greater than that of the bag, which comprises first stretchingthe bag about l5%-20% more than its original size, then relaxing byslightly releasing the stretching power on such bag, further stretchingthe bag an additional amount about equal to such first stretching, andfinally filling the so-finally-stretched bag.

3. Method of packaging a plurality of frankfnrters arranged inside-by-side relation, in a wrapper of elastic film, which comprisestransversely stretching a bag composed of such film having a bottom andside walls providing a mouth that is smaller than the transversedimensions of suoli frankfurters, with parallel preheated fingersextending into the bag, by moving such fingers away from one another toa limited extent, relaxing the so-stretched film by simultaneouslyretracting said fingers toward one another to an extent less than thatof such film stretching movement, and further stretching the sorelax'edfilm by again moving such fingers away from one another to an amount atleast equal to the first stretching, inserting frankfurthers through theso-enlarged mouth into the bag and against the bottom thereof to pushthe sofilled bag away from said fingers as the film contracts intoengagement with the frankfurters.

4. Method of packaging items in a bag of elastic film to yield a packagewherein the items are tightly wrapped and snugly conformed within thebag walls of the elastically stretched film, said bag, whose normalunstretched arenoso perimeter is smaller' than the maximum perimeter ofthe items transverse to their longitudinal axis, is simultaneouslyelastically stretched circumferentially along substantially its entirelength to a larger perimeter than the assembled items, at a packagingrate of the order of packages per minute, which comprises multistageexpanding and relaxing by slightly releasing the stretching power on thebag walls with stretching lingers, at a controlled rate, heating the bagand the stretching fingers, and expanding the bag simultaneouslycircumferentially along its entire length to a larger perimeter than thepredetermined perimeter of the assembled items, and finally filling thebag by advancing the product to the bag bottom to strip the bag from theexpanded fingers at a controlled rate.

5. A packaging machine comprising, in combination, means for partiallystretching an elastic film bag While indexing such bag from a loadingstation to a relaxing station, means acting to automatically relax theso-partially stretched bag in its partially stretched condition andsimultaneously heat it, means for fully stretching the bag whileindexing it to a content-filling station, and means for filling the sofully stretched bag and removing the so-lled bag from suchcontent-filling station, so that the bag compresses the contentsthereof.

6. Automatic packaging apparatus comprising, in combination, a rotaryturret head provided with four stations each comprising elastic film bagsupporting fingers, such stations consisting of a bag applying station,a bag heating and relaxing station, a product loading station, and afinger heating station, means for indexing said head through 90increments, means for automatically moving such lingers away from eachother to partially expand and stretch the bag thereon as the turret headis indexed to advance each bag from such bag applying station to saidbag heating and relaxing station, means for maintaining the spacing ofsuch partially expanded fingers at such bag heating and relaxing stationduring the dwell period and simultaneously heating such bag, meansacting to again move the fingers further away from each other as thehead is indexed to advance the so-relaxed bag from said bag heating andrelaxing station to` said product loading station, a plurality ofproduct trough units, means for successively advancing said producttrough units in line with the mouth of each bag as the latter ispositioned at said product loading station, means for pushing productssuccessively from such units transversely into such sostretched bag andsimultaneously stripping the so-illed bag from the fingers holding theso-stretched bag open, and automatically retracting such fingers as thehead is indexed to move them from such product loading station to thefinger heating station.

7. Method of packaging as defined by claim 3, which includes pushing thefrankfurters from a trough supporting them in generally parallelrelation as a substantially rectangular prism into the stretchedelastic-film bag positioned in alignment with such frankfurters in saidtrough to receive them which 4comprises pushing all of such frankfurtersgently at first and then more rapidly into Such bag and against thebottom thereof, Venting air thereby compressed in the bag therefrom,whereby damage to such frankfurters and the bag is minimized duringsubstantially high-speed operation.

S. The method defined in claim l which comprises the additional step ofradiantly heating the stretcher on which the envelopes are applied priorto applying the envelopes to heat soften and thereby favorably conditionthe film for subsequent stretching thereon.

9. rEhe method defined in claim 1 which comprises the additional step ofsimultaneously heating both the film and the stretcher after theenvelope is at least partially stretched thereon to warm and therebyfavorably condition the iilrn for further stretching.

References Cited by the Examiner UNITED STATES PATENTS 2,289,663 7/42Mallory 53-30 2,312,049 2/43 Pfeiffer 53184 X 2,331,762 itl/43 Brown53-30 2,884,328 4/59 lohnson 99-171 2,955,941 1G/ 6() Hultkrans et al.99-171 2,958,168 1l/6O Vogt 53-184 X 3,022,543 2/62 Baird et al. 99-1713,031,309 5/62 Muskat et al. 53-184 X A. LOUIS MONACELL, PrimaryExaminer.

ABRAHAM H. WINKELSTEIN, RAYMOND N.

JONES, Examiners.

2. METHOD OF FILING ELASTIC FILM BAGS WITH CONTENTS THE PERIMETER OFWHICH IS GREATER THAN THAT OF THE BAG, WHICH COMPRISES FIRST STRETCHINGTHE BAG ABOUT 15%-20% MORE THAN ITS ORGINIAL SIZE, THEN RELAXING BYSLIGHTLY RELEASING THE STRETCHING POWER ON SUCH BAG, FURTHER STRETCHINGTHE BAG AN ADDITIONAL AMOUNT ABOUT EQUAL TO SUCH FIRST STRETCHING, ANDFINALLY FILLING THE SO-FINALLY-STRETCHED BAG.
 5. A PACKAGING MACHINECOMPRISING IN COMBINATION, MEANS FOR PARTIALLY STRETCHING AN ELASTICFILM BAG WHICLE INDEXING SUCH BAG FROM A LOADING STATION TO A RELAXINGSTATION, MEANS ACTING TO AUTOMATICALLY RELAX THE SO-PARTIALLY STRETCHEDBAG IN ITS PARTIALLY STRETCHED CONDITION AND SIMULTANEOUSLY HEAT IT,MEANS FOR FULLY STRETCHING THE BAG WHILE INDEXING IT TO ACONTENT-FILLING STATION, AND MEANS FOR FILLING THE SO FULLY STRETCHEDBAG AND REMOVING THE SO-FILLED BAG FROM SUCH CONTENT-FILLING STATION, SOTHAT THE BAG COMPRESSES THE CONTENTS THEREOF.